Puerarin (formula (I), wherein R1=R2=R3=H) is an effective ingredient in Kudzuvine Root (Radix Puerariae), a leguminous plant, and has a chemical name of 4′,7-dihydroxy-8-β-D-C-glycosylisoflavone. In the recent decades, the mechanism and applications of puerarin are studied, and it is proven that puerarin does have effects such as expanding coronary artery, improving cardiac contractility, protection global ischemia cardiac muscle, promoting blood circulation, etc. At present, puerarin is widely used clinically for the treatment of coronary heart disease, angina pectoris, myocardial infarct, arrhythmia, cardiac failure, vertebro-basilar artery insufficiency, hyperviscosity syndrome, hypertension, cerebral thrombosis, cerebral edema, retinal arterial obstruction, retinal vein obstruction, sudden deafness, diabetes and complications thereof, pesticide intoxication, alcoholism, and tumors, etc. (Wang Jing, Ji Min, Hua Weiyi, et al., Study Achievement of Puerarin, Yaoxue Xuebao (Acta Pharmaceutica Sinica), 2003, 27(2):70-3). At present, cardio- and cerebrovascular diseases are the primary diseases causing adult death in China. Being a new drug for improving cardio- and cerebrovascular blood circulation, puerarin has a novel structure and definite therapeutic effects, and thus is important for the treatment of these diseases.
It has been reported in the prior arts that puerarin has some adverse effects in clinical applications, which mainly manifest in febrile, allergies, drug eruptions, transient hemoglobinuria, etc. Cheng Weijin, et al. (Yaowu Liuxingbing Zazhi (Chinese Journal of Pharmacoepidemiology), 2000, 9(3):129-130) had made an investigation on 568 patients who had administered with puerarin, and the results indicates that the total incidence rate of febrile was 5.81%, there was no significant difference in age and gender and in dosage, and the febrile mainly related to the days of sustained medication. The patients' body temperature gradually decreased to normal level after drug withdrawal or the patients were treated by antipyresis simultaneously. The treatment with antibiotics was ineffective. This might be caused by the toxic effect of drug accumulation during the long time of therapy; and the drug might penetrate the blood brain barrier, directly stimulate the center of thermoregulation in hypothalamus, affect the procedure of human body heat production and loss, and cause delayed allergy.
A series of simple alkyl esteric and etheric derivatives of puerarin had been synthesized via the modification of phenolic hydroxyl group and alditolic hydroxyl groups and their effects on blood flow of rabbit ocular tissue (Yang Ruolin, Li Na, et al., Zhongguo Yaoke Daxue Xuebao (Journal of China Pharmaceutical University), 1999, 30(2):81-85; Hou Dianjie, Wang Jianwu, Sun Jianlong, Zhongguo Yaowu Huaxue Xuebao (Chinese Journal of Medicinal Chemistry), 2002, 12(2):103-4). However, the pharmacodynamic actions and toxicities of these compounds on cardio- and cerebrovascular diseases, diabetes and alcoholism are not studied deeply.
In the prior arts, it is also disclosed that puerarin has poor water-solubility and lipo-solubility, and the solubility of puerarin in water is 0.462 g/100 ml. Solubilizers should be added during the preparations, and common solubilizers are propylene glycol, polyvinylpyrrolidone (PVP), etc. The solubility of puerarin in 4.3% PVP aqueous solution is 1.332 g/100 ml. The solubility of puerarin also depends on pH value, and puerarin in an aqueous solution has a poor stability at a relatively high pH value. The pH generally should be controlled at 6.5 or lower during the complexing and dissolving procedure (Wu Zhenghong, Zhu Yanqin, et al., Jiangsu Yaoxue Yu Linchuang Yanjiu (Jiangsu Pharmaceutical and Clinical Researches), 1999, 7(1): 9-12).
The prior art further discloses that puerarin has a relatively low oral bioavailability of about 30%, and is administered by intravenous injection in clinic. The poor water-solubility, oral bioavailability and adverse effects of puerarin render the value of puerarin as pharmaceuticals.
So far, no document has been found that relates to the puerarin-based compounds of the present invention, i.e., C-Glycosylisoflavones having alkylaminoalkoxyl substituent, and to the use of these compounds for the treatment and prevention of cardio- and cerebrovascular disease, diabetes, and chemical poisoning.